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ASTM A691 EFW Technical Overview
ASTM A691 is the standard specification for carbon and alloy steel pipe, electric-fusion-welded with filler metal added, fabricated from pressure-vessel-quality plate. Grade 1 (1-1/4 Cr) is made from A387 Grade 11 plate, and Grade 2 (2-1/4 Cr) is made from A387 Grade 22 plate. These pipes are intended for high-pressure service at high temperatures. Steel Emporium supplies A691 pipes in various classes (Class 11, 22, 42, etc.), which define the type of heat treatment and the extent of radiographic examination (X-Ray) performed on the weld seam. These are ideal for large-diameter applications in power plants and refineries where seamless pipes are not feasible.
Key Material Advantages
100% Weld Reliability
Welds are subjected to full radiography (RT) to ensure maximum integrity under pressure.
Large Diameter Capability
Excellent solution for large NB sizes (up to 100") in high-temp alloy service.
Thermal Stability
High chromium content ensures resistance to oxidation and creep at elevated heats.
| Grade | Equivalent Plate | Cr (Chromium) | Mo (Moly) | C (Carbon) | Si |
|---|---|---|---|---|---|
| Gr. 1 (1-1/4 Cr) | ASTM A387 Gr 11 | 1.00 - 1.50 | 0.44 - 0.65 | 0.05 - 0.17 | 0.50 - 0.80 |
| Gr. 2 (2-1/4 Cr) | ASTM A387 Gr 22 | 2.00 - 2.50 | 0.90 - 1.10 | 0.05 - 0.15 | 0.50 max |
| Grade | Tensile Strength (MPa) | Yield Strength (MPa) min | Elongation (% in 2") |
|---|---|---|---|
| A691 Grade 1 | 415 - 585 MPa | 205 MPa | 18% - 22% |
| A691 Grade 2 | 415 - 585 MPa | 205 MPa | 18% - 22% |
| Class | Heat Treatment | Radiography |
|---|---|---|
| Class 11 | None (As-rolled) | Full Radiography |
| Class 12 | None (As-rolled) | Spot Radiography |
| Class 22 | Stress Relieved (SR) | Spot Radiography |
| Class 42 | Normalized & Tempered | Spot Radiography |
| ASTM A691 Grade | A335 Seamless Equiv. | Plate Base | DIN Equivalent |
|---|---|---|---|
| Grade 1-1/4 Cr | A335 P11 | ASTM A387 Gr 11 | 13CrMo44 |
| Grade 2-1/4 Cr | A335 P22 | ASTM A387 Gr 22 | 10CrMo910 |
| Size (NB) | OD (mm) | STD Weight (kg/m) | XS Weight (kg/m) |
|---|---|---|---|
| 24" | 609.6 | 125.5 | 173.4 |
| 36" | 914.4 | 188.5 | 261.0 |
| 48" | 1219.2 | 251.5 | 348.6 |
Industrial Applications
Power Generation
High-pressure steam piping for large power plants.
Refineries
Thermal cracking and catalytic reformer units.
Fired Heaters
Large diameter convection and radiant heat lines.